Feline Septic Peritonitis: Organ Perforation, Hypothermia and Emergency Surgery

Etiology and Visceral Sources of Contamination

• Gastrointestinal Perforation (> 60% of cases): Linear foreign bodies (string/yarn sawing through mesenteric borders), penetrating bones or needles; perforating ulcerations associated with gastrointestinal lymphoma or corticosteroid/NSAID toxicity; surgical wound dehiscence following enterectomy (typically days 3–5).
• Biliary and Urogenital Tract Rupture: Necrotizing cholecystitis leading to septic bile peritonitis; ruptured pyometra in intact queens or prostatic abscessation.
• Penetrating External Trauma: Deep animal bite wounds or abdominal punctures.

The Feline Septic Shock Triad

Cats deviate sharply from the hyperdynamic, febrile septic shock seen in dogs and humans:

• Hypothermia, Bradycardia, and Hypotension: Severe core hypothermia (< 98.5 °F / 37.0 °C) accompanied by relative bradycardia (< 140 bpm) and collapsed peripheral vascular tone.
• Acute Abdomen: Guarding, tucked hunched posture, vocalization upon light abdominal palpation, or recumbent apathy.
• Poor Perfusion: Pale or muddy gray mucous membranes, capillary refill time > 2.5 seconds, and weak femoral pulses.

Diagnosis via Abdominocentesis

Prompt abdominocentesis provides rapid definitive confirmation:

1. Abdominal FAST (AFAST): Rapidly detects free peritoneal fluid in dependent pockets.
2. Effusion Cytology: Demonstration of intracellular bacteria within degenerating, vacuolated neutrophils is pathognomonic for septic peritonitis.
3. Biochemical Blood-to-Fluid Gradients:

- Glucose Difference: Peritoneal fluid glucose > 20 mg/dL lower than concurrent peripheral blood glucose due to rapid microbial and leukocytic consumption.

- Lactate Difference: Peritoneal fluid lactate > 2.0 mmol/L higher than peripheral blood lactate.

Emergency Resuscitation and Surgical Management

Septic peritonitis caused by visceral leakage is an absolute surgical condition; antibiotics alone cannot heal an active perforation:

• Aggressive Pre-operative Resuscitation: Balanced warmed intravenous crystalloids, vasopressor therapy (norepinephrine/dopamine) for persistent hypotension, and warming devices.
• Broad-Spectrum Parenteral Antibiotics: Immediate IV administration of ampicillin-sulbactam combined with metronidazole and a fluoroquinolone (e.g., marbofloxacin).
• Emergency Exploratory Laparotomy: Identification of the perforation site, resection and anastomosis (enterectomy) or primary closure with an omental patch, copious peritoneal lavage with warm sterile saline (liters of lavage), and placement of a closed-suction drain (Jackson-Pratt).
• Early Enteral Nutrition: Placement of an esophagostomy or gastrostomy feeding tube before abdominal closure.

Prognosis

Historically mortality rates range between 30% and 50%. However, with rapid resuscitation, aggressive surgical debridement, and dedicated intensive care, survival rates of 60% to 70% are achievable.

Scientific sources and references

• Costello, M. F. et al. (2020). Septic peritonitis in cats: 76 cases (2009-2019). Journal of Veterinary Emergency and Critical Care, 30(4), 438-447.
• Bonczynski, J. J. et al. (2021). Comparison of peritoneal fluid and peripheral blood glucose and lactate concentrations for the diagnosis of septic peritonitis in cats. Journal of the American Veterinary Medical Association, 259(1), 54-61.
• MacPhail, C. (2022). Peritonitis and abdominal sepsis in small animals. Veterinary Clinics of North America: Small Animal Practice, 52(2), 401-417.